Recently, information recording and playback apparatuses using hard disk drive (hereinafter referred to as HDDs) devices have started to be widely used for portable music players and mobile phones. There is a need for a further reduction in the size of such information recording and playback apparatuses, and, in accordance with this need, there is a tendency to reduce the size of HDDs. Under such conditions, HDDs that include magnetic disks, which are information recording media and are smaller than 1 inch (25.4 mm), are required to have high capacity.
To achieve the object of obtaining high capacity, efforts have continuously been made to achieve high-density and high-speed to correspond to a twofold increase in the area density of the magnetic disk (tracks×line density) by employing technologies for increasing the performance of the magnetic head based on a vertical magnetization method and for decreasing the flying height to several tens of nanometers or smaller. In this way, high density and high speed, which are a natural consequence of for achieving high capacity, cause the generation of data reading and writing errors, which has become a great problem.
One cause of such reading and writing errors is magnetic leakage flux from the motor device of the HDD. As a technique to solve this problem, Patent Document 1 listed below proposes an apparatus whose head has a movement trajectory positioned at an intermediate section between projecting cores.
Patent Document 1:
PCT International Publication No. WO00/62404 Pamphlet (p. 12, FIGS. 6 and 9)